This invention relates generally to protective coatings. More specifically, the invention relates to a protective coating which is water removable and which can be applied to a variety of surfaces to aid in the removal of paint overspray therefrom.
In many industrial applications, high volume, high speed painting operations are carried out in facilities often referred to as spray booths. Paint overspray builds up on the walls, floor gratings and other structures of the booth. Likewise, paint overspray accumulates on conveyors, racks and other equipment which transports articles through a paint spray facility. It is necessary to periodically remove built up paint overspray. In order to facilitate the ready removal of such paint overspray, a variety of protective coatings have been developed. These coatings are applied to equipment and structures which come in contact with paint overspray, and function to decrease the adherence of the paint. Such coatings typically include various polymeric materials, oils, greases, waxes and the like.
Ideally, a protective coating used in such applications prevents adherence of both solvent and water-based paints to underlying structures. The coatings should also allow for ready removal of the paint, preferably by washing with a relatively low pressure stream of water. In addition, coatings should be reasonably well adherent to the structures and they should not adversely interfere with the painting process. The coating should also be low in toxicity, and preferably low in cost.
The prior art has implemented a variety of protective coating compositions.
U.S. Pat. Nos. 5,876,791 and 6,117,485 disclose the use of dextrin-based compositions which are dried onto a surface in order to protect it from paint overspray.
U.S. Pat. No. 5,603,992 describes a method for protecting an activated plastic surface by application of a compound containing dextrin, cellulose or a cellulose derivative.
U.S. Pat. No. 5,418,006 discloses a two step method for protecting a surface in which the surface is first treated with a water repellent substance and then coated with an aqueous composition.
U.S. Pat. No. 5,308,647 details a composition comprising water soluble polyglycerols and methods for use in masking areas of a surface to prevent overspray.
U.S. Pat. No. 6,191,097 discloses a biodegradable solvent composition.
While specific prior art coatings work well in particular applications, heretofore employed, compositions are generally not usable with both water and solvent-based paints. In addition, many of the prior art compositions employ relatively expensive polymeric components. As will be explained in detail hereinbelow, the present invention provides a protective coating composition which prevents adherence of both solvent and water-based paints to a variety of substrates. The coating of the present invention is water removable. In addition, it does not contain any volatile organic compounds or toxic materials and is relatively low in cost.
Disclosed herein is a water removable protective coating which is comprised of a hydrophobic solvent which is a C1-C4 alkyl ester of a C16-C18 fatty acid, together with a surfactant in an amount sufficient to render the hydrophobic solvent water dispersible. The composition may further include a thickening agent. In specific embodiments, the hydrophobic solvent comprises at least 70%, by weight, of the composition, and in specific embodiments it comprises at least 90% by weight of the composition. The surfactant may comprise 0.1-10% by weight of the composition, and may comprise a nonionic or ionic surfactant.
Also disclosed herein is a process for temporarily protecting a surface from overspray by applying a protective composition to the surface wherein the protective composition is comprised of a hydrophobic solvent, a surfactant, and a thickening agent. The protective coating may be removed from the surface by a fluid stream, such as a stream of low pressure water.